Plasticized polypropylene thermoplastics

ABSTRACT

The invention is directed to a plasticized polypropylene thermoplastic composition comprising a blend of A) from 50 to 99.9 wt % of a thermoplastic polymer derived from polypropylene, optionally with one or more copolymerizable monomer selected from C 2 -C 10  α-olefin or diolefin, said polymer having a melt flow rate (MFR) (ASTM D1238) of from 0.5 to 1000 and a crystallinity by differential scanning calorimetry of from 0 to 70%; B) from 0.1 to 50 wt % of at least one ethylene copolymer having a weight-average molecular weight (M w ) (GPC) of from 500 to 10,000, a molecular weight distribution (MWD) (GPC) of from greater than 1.5 to less than or equal to 3.5, and a comonomer content of from greater than or equal to 20 mol % to less than 70 mol %; and optionally, C) from 0 to 20 wt % of a thermoplastic polypropylene modifier compound other than that of B).

RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.09/390,235, Filed Sep. 2, 1999 (Allowed); and incorporates by referencethe entire disclosure of Ser. No. 09/390,235.

FIELD OF INVENTION

This invention relates to hydrocarbon plasticizers for polypropylenethermoplastics.

BACKGROUND

The blending of plasticizers in general with thermoplastics and theresulting plasticization of those thermoplastics are well known and manyreviews have been written. A plasticizer is generally an organiccompound incorporated into a high polymer, such as for example athermoplastic, to desirably facilitate processing, increase itsworkability, flexibility, and/or distensibility of the polymer.

Within the last few years efforts have been made in the field ofplasticizers to better understand factors which governplasticizer/thermoplastic miscibility. Examples of a thermoplastic andplasticizer include polypropylene and low molecular weight polyolefins,respectively. Polypropylene is an inexpensive polyolefin engineeringthermoplastic that is generally stiff and even brittle below roomtemperature especially for highly stereoregular polypropylene.Tackifiers are examples of low molecular weight polyolefinsplasticizers. Examples of tackifiers include hydrocarbon resins derivedfrom fractionated petroleum distillates, coal tar, turpentine fractionsand from copolymerization of pure aromatic monomers. However, thesetackifiers typically have high glass transition temperature (T_(g)) andhigh solubility parameter. As such, upon blending, these tackifiers tendto raise the T_(g) of the polypropylene. Increasing the T_(g) increasesthe stiffness of polypropylene.

Other plasticizers, which have low T_(g,) (below −20° C.) such asethylene-propylene rubber, ethylene-butene copolymer (having a M_(w)greater than or equal to 20,000), are immiscible with the polypropylene.Plasticizers which are immiscible with polypropylene tend to collect onthe surface of the manufactured article, hinder the manufacturingprocess of articles made therefrom and may cause the resulting productto have generally undesirable features.

Because polypropylene is an inexpensive thermoplastic, there exists aneed to improve its workability and to overcome its inherent stiffnessand brittleness which limit its commercial application. Therefore, aneed exist to safely and economically improve the workability,flexibility, and/or distensibility of polypropylene.

SUMMARY OF THE INVENTION

Miscible blends of polypropylene with low molecular weight ethyleneα-olefin copolymer plasticizers have been discovered. By blending suchmiscible, low molecular weight ethylene α-olefin copolymer plasticizerswith polypropylene (isotactic polypropylene, syndiotactic polypropyleneand atactic polypropylene), the glass transition temperature, storagemodulus and viscosity of the blended polypropylene are lowered. Bydecreasing the transition temperature, storage modulus and viscosity,the workability, flexibility, and distensibility of polypropyleneimproves. As such, broadened commercial application for these newpolypropylene blends in film, fibers and molded products is apparent.Furthermore, the flexibility of a product design utilizing these novelblends can be further extended by taking advantage of the enhancedcomonomer incorporation and tacticity control possible with metallocenecatalysts, both of which can reduce isotactic polypropylene (“iPP”)crystallinity prior to blending with the low molecular weight ethyleneα-olefin copolymer plasticizers.

In one embodiment, a plasticized polypropylene thermoplastic isprovided. The plasticized polypropylene thermoplastic includes from 50to 99.9 weight percent (“wt %”) of a thermoplastic polymer derived frompolypropylene. Optionally, the thermoplastic polymer is copolymerizablewith one or more monomers selected from C₂-C₁₀ α-olefin or diolefin. Thethermoplastic polymer desirably has a melt flow rate (MFR) (ASTM D1238)in the range of from 0.3 to 1000 and a crystallinity, determined bydifferential scanning calorimetry (DSC) at a scan rate of 10° C. perminute, in the range of from 0 to 70% crystallinity. The thermoplasticpolymer is blended with from 0.1 to 50 wt % of at least one ethylenecopolymer. The ethylene copolymer desirably has a weight-averagemolecular weight (M_(w)) (GPC) of from 500 to 10,000, a molecular weightdistribution (MWD) (GPC) of from greater than 1.5 to less than or equalto 3.5, and a comonomer content of from greater than or equal to 20 mol% to less than 70 mol %. The plasticized polypropylene thermoplastic mayinclude from 0 to 20 wt % of the polypropylene thermoplasticcomposition, of a thermoplastic polypropylene modifier compound otherthan the ethylene copolymer described above. Examples of thermoplasticpolypropylene modifier compounds include one or more compositionsselected from the group which includes antioxidants, fillers, pigments,hydrocarbon resins, rosins or rosin esters, waxes, UV stabilizers,additional plasticizers, and tackifiers such as ESCOREZ, a product ofExxon Chemical, which is more fully described in U.S. Pat. No. 5,317,070which is incorporated by reference herein. Additionally, the terminalvinylidene groups present on some of the above thermoplasticpolypropylene modifier compounds may be functionalized, suchfunctionalization being more fully described in U.S. Pat. Nos. 5,763,556and 5,498,809, both of which are incorporated by reference herein.

The ethylene copolymer may be further described as having a glasstransition temperature (T_(g)) of from greater than or equal to −80° C.to less than or equal to −30° C. In another embodiment, the ethylenecopolymer may be described as having an ethylene crystallinity, asdetermined by differential scanning calorimetry (DSC) at a scan rate of10° C. per minute of less than or equal to 5% crystallinity.

In another embodiment, the plasticized polypropylene thermoplastic maybe further described as having a crystallinity by DSC at a scan rate of10° C. per minute of less than 60% and wherein the wt % of said ethylenecopolymer present in the plasticized polypropylene thermoplastic is lessthan or equal to y, wherein y is in the range of 0.1 to 50, asdetermined by y in the equationy=50−0.5xwhere x=the % crystallinity of the thermoplastic polymer.

In another embodiment, the thermoplastic polymer may be furtherdescribed as having a crystallinity by DSC at a scan rate of 10° C. perminute of greater than or equal to 60% and wherein the wt % of saidethylene copolymer present in the plasticized polypropylenethermoplastic can be as high as 20.

In another embodiment, the ethylene copolymer component may include, inaddition to ethylene, one or more of C₃ to C₂₀ linear or branchedα-olefin or diolefin. Desirably, the ethylene copolymer may be either anethylene-propylene, ethylene-butene copolymer, ethylene-hexenecopolymer, ethylene-octene copolymer, ethylene norbornene, ethylenestyrene copolymers, and ethylene-isobutylene copolymers or mixedmonomers including ter-, tetrapolymers, and the like, thereof.

In another embodiment, a plasticized polypropylene thermoplasticcomposition is provided which includes a blend of a thermoplasticpolymer and the ethylene copolymer. The thermoplastic polymer isdesirably derived from amorphous propylene. Desirably, from 50 to 99.9wt % of the plasticized polypropylene thermoplastic is the thermoplasticpolymer. Optionally the thermoplastic polymer may include one or morecopolymerizable monomers selected from C₂-C₁₀ α-olefin or diolefin. Thethermoplastic polymer has melt flow rate (MFR) (ASTM D1238) in a rangefrom 0.3 to 1000 and a crystallinity, as determined by differentialscanning calorimetry (DSC at a scan rate of 10° C. per minute), in arange from 0 to less than 5%. Desirably, from 0.1 to 50 wt % of theplasticized polypropylene thermoplastic is the ethylene copolymer. Theethylene copolymer has a weight-average molecular weight (M_(w)) (GPC)in a range from 500 to 10,000, a molecular weight distribution (MWD)(GPC) in a range from greater than 1.5 to less than or equal to 3.5, anda comonomer content in a range from greater than or equal to 20 mol % toless than 70 mol %. The plasticized polypropylene thermoplastic may alsoinclude from 0 to 20 wt % thereof of a thermoplastic polypropylenemodifier compound other than the ethylene copolymer. Examples of thisthermoplastic polypropylene modifier include, but are not limited to,antioxidants, fillers, pigments, hydrocarbon resins, rosins or rosinesters, waxes, UV stabilizers, additional plasticizers, singularly or incombination.

In another embodiment, the plasticized polypropylene thermoplastic maybe further described as having a crystallinity by DSC at a scan rate of10° C. per 5 minute of less than 5% and wherein the wt % of saidethylene copolymer present in the plasticized polypropylenethermoplastic is less than or equal to y, wherein y is in the range of0.1 to 50, as determined by y in the equationy=50−0.5xwhere x=the % crystallinity of the thermoplastic polymer.

In another embodiment, a plasticized polypropylene thermoplasticcomposition is provided which includes a blend of a thermoplasticpolymer and the ethylene copolymer wherein the wt % of the ethylenecopolymer in the plasticized polypropylene thermoplastic is less than orequal to y, wherein y is in the range of 0.1 to 50, as determined by yin the equationy=50−0.5xwhere x=the % crystallinity of said thermoplastic polymer. Thethermoplastic polymer is derived from polypropylene, optionally with oneor more copolymerizable monomer selected from C₂-C₁₀ α-olefin ordiolefin, said thermoplastic polymer having a melt flow rate (MFR) (ASTMD1238) of from 0.3 to 1000. The ethylene copolymer has a weight-averagemolecular weight (M_(w) ) (GPC) of from 500 to 10,000, a molecularweight distribution (MWD) (GPC) of from greater than 1.5 to less than orequal to 3.5, and a comonomer content of from greater than or equal to20 mol % to less than 70 mol %. In one embodiment, from 50 to 99.9 wt %of the plasticized polypropylene thermoplastic 25 is derived from thethermoplastic polymer and from 0.1 to 50 wt % of the plasticizedpolypropylene thermoplastic is derived from the ethylene copolymer.

Desirably, the crystallinity, by differential scanning calorimetry (DSCat a scan rate of 10° C. per minute), of the thermoplastic polymer is ina range of from 0 to 70%.

In another embodiment, a plasticized polypropylene thermoplasticcomposition formed from a blend of a thermoplastic polymer and anethylene copolymer is provided. The thermoplastic polymer derived frompolypropylene, optionally with one or more copolymerizable monomerselected from C₂-C₁₀ α-olefin or diolefin, said thermoplastic polymerhaving a melt flow rate (MFR) (ASTM D1238) of from 0.3 to 1000. Theethylene copolymer has a weight-average molecular weight (M_(w)) (GPC)of from 500 to 10,000, a molecular weight distribution (MWD) (GPC) offrom greater than 1.5 to less than or equal to 3.5, and a comonomercontent of from greater than or equal to 20 mol % to less than 70 mol %.The wt % of the ethylene copolymer in the thermoplastic composition isless than or equal to y, wherein y is in the range of 0.1 to 50, asdetermined by y in the equationy=50−0.5xwhere x=the % crystallinity of said thermoplastic polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the relationship between the wt % copolymer presentin the plasticized polypropylene thermoplastic and % crystallinity ofthe plasticized polypropylene thermoplastic.

FIG. 2 illustrates dynamic mechanical thermal analysis measurements of a50:50 blend of atactic polypropylene and Copolymer 1 (an ethylene-butenecopolymer, see Table 1).

FIG. 3 illustrates a tan δ peak for the blend in FIG. 2.

FIG. 4 illustrates NMR relaxation measurements (T_(1ρH)) for a blend ofatactic polypropylene and Copolymer 2 (an ethylene-butene copolymer, seeTable 1).

FIG. 5 illustrates the decreasing effect on Young's modulus of isotacticpolypropylene by blending Copolymers 1-3 therewith (Copolymer 3 is anethylene-butene copolymer, see Table 1).

FIG. 6 illustrates that energy-to-break for the tensile bars increasesover 50% due to addition of ˜5-15 wt % plasticizer.

FIG. 7 illustrates a hysterisis series of tensile curves for 60:40 wt:wtblend of elastomeric polypropylene and Copolymer 2.

DETAILED DESCRIPTION OF THE INVENTION

This invention relates to (1) plasticized polypropylene thermoplasticcompositions, particularly miscible blends of polypropylene with lowmolecular weight ethylene α-olefin copolymer plasticizers; (2) methodsfor making plasticized polypropylene thermoplastic compositions; and (3)products made from plasticized polypropylene thermoplastic compositions.These are described in turn below.

As used herein, “isotactic” is defined as having at least 95% isotactic(meso) pentads according to analysis by ¹³C-NMR. As used herein, “highlyisotactic” is defined as having at least 99% isotactic pentads accordingto analysis by ¹³C-NMR.

As used herein, “amorphous” is defined as having less than 5%crystallinity as measured by DSC at a scan rate of 10° C. per minute.

As used herein, “molecular weight” means weight average molecular weight(M_(w)) and “molecular weight distribution,” (MWD), means M_(w) dividedby number average molecular weight (M_(n)) as determined by gelpermeation chromatography (GPC). As used herein, unless otherwisestated, “polymerization” means homopolymerization.

The plasticized polypropylene thermoplastics described herein are ablend of a thermoplastic polymer and an ethylene copolymer. This blendmay also include thermoplastic polypropylene modifiers. These modifiersmay be included in the plasticized polypropylene thermoplasticcompositions. Such modifiers (also known as additives) and their use aregenerally well known in the art.

Ethylene Copolymer Compositions

Generally, ethylene copolymers suitable for blending with thethermoplastic polymer, including amorphous and isotactic thermoplasticpolymers, desirably have a weight-average molecular weight (M_(w)) (GPC)of from 500 to 10,000, a molecular weight distribution (MWD) (GPC) offrom greater than 1.5 to less than or equal to 3.5, and a comonomercontent of from greater than or equal to 20 mol % to less than 70 mol %.The wt % of at least one ethylene copolymer present in the plasticizedpolypropylene thermoplastic composition may be from 0.1 to 20 wt %,desirably from 1.0 to 15 wt % and more desirably from 1.0 to 10 wt %.Specific examples of ethylene copolymers include, but are not limited toethylene-propylene, ethylene-butene, ethylene-hexene, andethylene-octene copolymers. Additionally, the ethylene copolymerdesirably has a glass transition temperature (T_(g)) in the range fromgreater than or equal to −80° C. to less than or equal to −30° C., moredesirably from −75° C. to −45° C., most desirably, from −70° C. to −45°C.

Table 1 illustrates the glass transition temperatures, measured by DSCat a scan rate of 10° C. per minute, molecular weights and comonomerconcentration of three ethylene/butene copolymers.

DSC was measured on a TA Instruments model number 2910. Generally, DSCis a measure of the heat flow into or away from a sample polymer. Thesample polymer is placed in one heating chamber, a reference materialinto a separate heating chamber. The sample and a reference material areheated at a predetermined rate until heat is emitted or consumed by thesample. The DSC circuitry is programmed to maintain the same temperaturefor both the reference and sample chambers. The current necessary tomaintain a constant temperature between the sample and reference isrecorded. This data provide a direct measure of the heat of transitionof the sample. TABLE 1 Ethylene Mole % Copolymer comonomer M_(w), GPC Tg(Liquid) (butene) (PE std) (DSC, ° C.) Copolymer 1 33.3 7550 −71(−45)^(a) Copolymer 2 60 8780 −55.3 Copolymer 3 66.7 6550 −61.2^(a)Small second transition in DSC.

Table 1A illustrates the molecular weights and comonomer concentrationof two ethylene/propylene copolymers. TABLE 1A Ethylene Mole % Copolymercomonomer M_(W), GPC Tg (Liquid) (propylene) (PE std) (DSC, ° C.)Copolymer 4 38 21,900 Not Measured Copolymer 5 42 3400 −76.0(−52)^(a)^(a)Small second transition in DSC.

Copolymers 1-5 may be made in a high pressure reactor. An example ofsuch a high pressure reactor would be a staged and baffled reactor (5zones) and have a reactor volume 750 liters, and a 6:1 length/diameterdimension. The residence time in such a reactor may be between 1-2minutes.

More particularly, the polymerization conditions for copolymers 1-5would include a stirred 750 liter steel autoclave reaction vessel whichis equipped to perform continuous Ziegler-Natta (Z-N), metallocene orother single site catalyst polymerization reactions at pressures up to2500 bar and temperature up to 300° C. The reactor system may beequipped with instrumentation, such as thermocouples and pressuretransducers to continuously monitor temperature and pressure andcontinuous feed systems to continuously supply purified compressedmonomers (e.g., ethylene, butene-1). Additional equipment may alsoinclude a continuous catalyst feed system, a rapid venting and quenchingsystem, and a product separation and collection system. Thepolymerization may be performed without the addition of any externalsolvents. The reactor contents may be stirred continuously duringpolymerization. A typical stirring rate may be about 2,000 rpm. Thetemperature in the reactor may be established and maintained at a targetlevel, such as between 100° C. and 220° C. by pumping the catalystsolution using a continuous high pressure injection pump. See forexample, U.S. Pat. Nos. 5,084,534 and 5,408,017 incorporated byreference for purposes of US patent practice.

Following polymerization, the polymerized product may be separated andanalyzed, for such purposes as quality control and the like. Theunreacted ingredients may be transported via a recycle loop through acooler and compressor and returned back to the autoclave reactor, alongwith fresh monomer. As will be recognized by those skilled in the art ofhigh pressure Z-N polymerization, the process allows considerableflexibility to modify the molecular weights and copolymer composition,among other parameters of the polymerized products.

More specific reactor conditions may include the use ofMe₂Si(H₄-Indenyl)₂ ZrCl₂ as the catalyst and methyl alumoxane (MAO) asthe co-catalyst. The Al/transition metal molar ratio may range from 50:1to 500:1. Reactor pressure may be 20,000 psi or approximately 1350 bar.The reactor exit temperature may be in the range of between 300° F. to370° F., depending upon the target molecular weight. The compositionfeed may be 90 mole % butene-1 and 10 mole % ethylene to achieve atarget 50 wt % incorporation of butene-1 into the ethylene copolymer.Under these conditions, a production rate of around 2750 lbs/hr. may beachieved.

The viscosity measurements for copolymers 1, 3-5 are provided in Table2.In keeping with the GPC molecular weight measurements, the viscosityof Copolymer 1 is higher than that of Copolymer 2. These viscositieswere measured using a Brookfield Viscometer. TABLE 2 Viscosity ViscosityLiquid (cP @ ° C.) 50 60 70 90 Copolymer 5 1255  715  485 1200  695  445200 50 70 90 110 Copolymer 1 8810 2850 1230 2910 1250 580 Copolymer 36010 1880  730 1840  750 360 110 120 140 Copolymer 4 54,500   39,800  22,800  

The wt % of the ethylene copolymer present in the plasticizedpolypropylene thermoplastic may be described by Equation 1, wherein thewt % of the copolymer is less than or equal to y, wherein y is in therange of 0.1 to 50, as determined by y in Equation 1:y=50−0.5xwhere x=the % crystallinity of the thermoplastic polymer composition(described in greater detail below). The relationship between wt %copolymer present in the plasticized polypropylene thermoplastic and %crystallinity is further illustrated in FIG. 1.Thermoplastic Polymer Compositions

Generally, thermoplastic polymers suitable for use in this invention maybe derived from propylene or may be copolymerized with small amounts,generally from 0.1 to 10 mol. % of one or more monomers selected fromC₂-C₁₀ α-olefins or diolefins such as for example, ethylene, butene-1,hexene-1 and octene-1. These thermoplastic polymers include copolymersand homopolymers and blends, including reactor blends, of amorphouspolypropylene, isotactic polypropylene, and metallocene catalyzedpolypropylenes. These thermoplastic polymers may have a molecular weightdistribution that is in the range of from about 2.0 to about 20.0,desirably from about 2.0 to about 12.0, even more desirably from about2.0 to about 8.0.

The thermoplastic polymers compositions of this invention may have aweight average molecular weight (M_(w)) that is in the range of fromabout 60,000 to about 750,000, and desirably from about 100,000 to about500,000, and most desirably from about 150,000 to about 400,000. Thesethermoplastic polymer compositions may have a melt flow rate (MFR) thatis in the range of from about 0.2 dg/min to about 30 dg/min, desirablyfrom about 0.5 dg/min to about 20.0 dg/min, even more desirably fromabout 1.0 dg/min to about 10.0 dg/min. The melting point of thethermoplastic polymer may be less than about 162° C., desirably lessthan about 155° C., and most desirably less than about 150° C. Upperlimits for melting point depend on the specific application but wouldtypically not be higher than 170° C. The hexane extractables level (asmeasured by 21 CFR 177.1520(d)(3)(i)) of the these thermoplasticpolymers may be less than 2.0 wt %, and desirably less than 1.0 wt %.

The thermoplastic polymers of this invention can be blended with otherpolymers, particularly with other polyolefins. Specific examples ofthermoplastic polymers include, but are not limited toethylene-propylene rubber, ethylene-propylene propylene diene rubber,and ethylene plastomers. Specific examples of commercially availableethylene plastomers include EXACT™ resins products of Exxon ChemicalCompany and, AFFINITY™ resins and ENGAGE™ resins, products of DowChemical Company.

Thermoplastic Polypropylene Modifier

Thermoplastic polypropylene modifiers may be those commonly employedwith plastics. Examples include one or more of the following: heatstabilizers or antioxidants, neutralizers, slip agents, antiblockagents, pigments, antifogging agents, antistatic agents, clarifiers,nucleating agents, ultraviolet absorbers or light stabilizers, fillers,hydrocarbon resins, rosins or rosin esters, waxes, additionalplasticizers and other additives in conventional amounts. Effectivelevels are known in the art and depend on the details of the basepolymers, the fabrication mode and the end application. In addition,hydrogenated and/or petroleum hydrocarbon resins and other plasticizersmay be used as modifiers.

The plasticized polypropylene thermoplastic composition may include from0 to 20 wt % of a thermoplastic polypropylene modifier compound otherthan the ethylene copolymer. Desirably, the thermoplastic polypropylenemodifier constitutes greater than 0.001 wt % of the plasticizedpolypropylene thermoplastic composition.

Metallocene Catalyzed Thermoplastic Polymers

The preparation of metallocene catalyzed thermoplastics and particularlymetallocene catalyzed polypropylene involves the use of metallocenecatalyst systems. Metallocene catalyst systems include a metallocenecomponent and at least one activator. Desirably, these catalyst systemcomponents are supported on support materials, such as inorganic oxideor polymeric materials.

Metallocenes

As used herein “metallocene” and “metallocene component” refer generallyto compounds represented by the formula Cp_(m)MR_(n)X_(q) wherein Cp isa cyclopentadienyl ring which may be substituted, or derivative thereofwhich may be substituted, M is a Group 4, 5, or 6 transition metal, forexample titanium, zirconium, hafnium, vanadium, niobium, tantalum,chromium, molybdenum and tungsten, R is a hydrocarbyl group orhydrocarboxy group having from one to 20 carbon atoms, X is a halogen,and m=1-3, n=0-3, q=0−3, and the sum of m+n+q is equal to the oxidationstate of the transition metal.

Methods for making and using metallocenes are very well known in theart. For example, metallocenes are detailed in U.S. Pat. Nos. 4,530,914;4,542,199; 4,769,910; 4,808,561; 4,871,705; 4,933,403; 4,937,299;5,017,714; 5,026,798; 5,057,475; 5,120,867; 5,278,119; 5,304,614;5,324,800; 5,350,723; and 5,391,790 each fully incorporated herein byreference.

Methods for preparing metallocenes are fully described in the Journal ofOrganometallic Chem., volume 288, (1985), pages 63-67, and inEP-A-320762, both of which are herein fully incorporated by reference.

Desirable metallocene catalyst components are described in detail inU.S. Pat. Nos. 5,145,819; 5,243,001; 5,239,022; 5,329,033; 5,296,434;5,276,208; 5,672,668; 5,304,614; 5,374,752; 5,240,217; and 5,643,847;and EP 549 900 and 576 970 all of which are herein fully incorporated byreference.

Additionally, metallocenes such as those described in U.S. Pat. No.5,510,502 (incorporated herein by reference) are suitable for use inthis invention.

Activators

Metallocenes are generally used in combination with some form ofactivator. Alkylalumoxanes are desirably used as activators, mostdesirably methylalumoxane (MAO). There are a variety of methods forpreparing alumoxane, non-limiting examples of which are described inU.S. Pat. Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419,4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032,5,248,801, 5,235,081, 5,103,031 and EP-A-0 561 476, EP-B1-0 279 586,EP-A-0 594-218 and W094/10180, each fully incorporated herein byreference. Activators will also include those comprising or capable offorming non-coordinating anions along with catalytically activemetallocene cations. Compounds or complexes of fluoro aryl-substitutedboron and aluminum are particularly suitable, see, e.g., U.S. Pat. Nos.5,198,401; 5,278,119; and 5,643,847.

Support Materials

The catalyst systems used in the process of this invention mayoptionally be supported using a porous particulate material, such as forexample, talc, inorganic oxides, inorganic chlorides and resinousmaterials such as polyolefin or polymeric compounds.

The most preferred support materials are porous inorganic oxidematerials, which include those from the Periodic Table of Elements ofGroups 2, 3, 4, 5, 13 or 14 metal oxides. Silica, alumina,silica-alumina, and mixtures thereof are particularly preferred. Otherinorganic oxides that may be employed either alone or in combinationwith the silica, alumina or silica-alumina are magnesia, titania,zirconia, and the like.

The supported catalyst system may be used directly in polymerization orthe catalyst system may be prepolymerized using methods well known inthe art. For details regarding prepolymerization, see U.S. Pat. Nos.4,923,833; 4,921,825; and 5,643,847; and EP 279 863 and EP 354 893 (eachfully incorporated herein by reference).

Incorporation of the Thermoplastic Polymer with the Ethylene Copolymer

The plasticized polypropylene thermoplastics may be formed by blendingthe thermoplastic polymer with the ethylene copolymer. For smallquantities sufficient for laboratory examination and analysis, a mixer,such as a Brabender mixer, will be sufficient. For larger or commercialquantities, the liquid ethylene copolymer may be pumped directly into anextruder zone containing the melted thermoplastic polymer.

The plasticized polypropylene thermoplastics of this invention arecompositions that can be effectively used in many if not all of the usesknown for polypropylene compositions. These uses include, but are notlimited to: hot melt adhesives; pressure sensitive adhesives (as anadhesive component, particularly when the polypropylene has low levelsof crystallinity, e.g., amorphous polypropylene); films (whetherextrusion coatings, cast or blown; such will exhibit improved heatsealing characteristics); sheets (such as by extrusion in single ormultilayer sheets where at least one layer is a plasticizedpolypropylene thermoplastic composition of the invention); any ofmeltblown or spunbond fibers; and, as thermoplastic components inthermoformable thermoplastic olefin (“TPO”) and thermoplastic elastomer(“TPE”) blends where polypropylene has traditionally been demonstratedto be effective. In view of these many uses, with improved lowtemperature properties and increased workability, the plasticizedpolypropylene thermoplastics offer a suitable replacement in selectedapplications for plasticized polyvinyl chloride (PVC).

The following examples are presented to illustrate the foregoingdiscussion. All parts, proportions and percentages are by weight unlessotherwise indicated. Although the examples may be directed to certainembodiments of the present invention, they are not to be viewed aslimiting the invention in any specific respect.

EXAMPLES Example 1

The glass transition temperatures measured by dynamic mechanical thermalanalysis (“DMTA”—tan δ peak) for blends of plasticizer liquids andelastomeric polypropylene (ePP) and amorphous polypropylene (aPP) arelisted in Table 3.

DMTA measurements were determined by placing approximately 0.8 grams ofthe sample in a Rheometrics 25 mm vacuum mold. A plunger is insertedinto the mold, using a 1″ spacer to hold the plunger above the vacuumport. This assembly is placed in a Carver press. The sample chamber isevacuated for at least 5 min. at ambient temperature and then heated to190° C. and held at that temperature for 10 min. while still undervacuum. After this period, the press heater is turned off, the spacerremoved, and 5,000 lbs. of pressure applied while a nitrogen purge ispassed through the mold cooling port. Once the sample has cooled to roomtemperature, the plunger is pushed out of the mold using a press and theplunger removal tool. Cooling to lower temperature may be required forsamples that cannot easily be removed from mold faces.

Using a 13 mm wide bar cutter, the sample is cut to size (1 to 2 mm×13mm×20 mm) for DMTA test just prior to use. The Polymer Labs DMTA iscalibrated for the A, B and C transducer stiffness settings. L frame andC sample clamps are used for mounting the sample. The test parametersinclude a single cantilever; peak to peak displacement of 64 microns(less for stiffer samples), frequency of 1 or 10 Hz, start temperatureof −140° C., max temperature of 150° C. Temperature is increased at arate of 3° C./min.

Tan δ is the ratio of E″/E′ where E″ is the loss modulus and E′ is theelastic modulus or storage modulus.

These measurements clearly show a pronounced depression in the T_(g) ofthe polypropylene from ˜273-276° K. Also shown in Table 3 are calculatedT_(g)'s based on equation (2).1/T _(g) =w ₁ /T _(g1) +w ₂ /T _(g2)

where w₁ is the weight fraction of component 1, T_(g1) is the glasstransition temperature of component 1, w₂ is the weight fraction ofcomponent 2, and T_(g2) is the glass transition temperature of component2. TABLE 3 Comparison of Measured (DMTA) and Calculated Tg ofPlasticized Amorphous Polypropylenes Blend Tg Measured Tg Calc^(d) α-PP(wt %) Copolymer (wt %) (° K) (° K) e-PP^(a) (60) Copolymer 2 (40) 256249 a-PP(50)^(b) Copolymer 6^(c) (50) 258 — a-PP(50) Copolymer 2 (50)245 243 a-PP(50) Copolymer 3 (50) 249 238 a-PP(50) Copolymer 1 (50) 242233^(a)Molecular weight characterization of this polymer (GPC-VIS): MN =15k; MW = 302.5k; MZ = 762.6k, and crystallinity (˜5% based on DSC).Prepared in accordance with the G. W. Coates and R. M. Waymouth paperappearing in “Science”, vol. 267, p. 217 (1995) incorporated byreference herein.^(b)Amorphous polypropylene polymerized at 90° C. for 40 min. using amono(cyclopentadienyl)Ti(4+) catalyst activated with MAO (constant Al/Tiratio) in hexane. This amorphous polypropylene contained between 4.9 and6.3% 2,1 defect insertions by no 1,3 insertions and ˜60% racemic triadsand ˜40% meso triads. GPC-VIS data MW ˜274.1k; MWD = 2.3. Thepolymerization process is described# in greater detail in U.S. Pat. No. 5,420,217 which is incorporated byreference herein.^(c)high molecular weight (M_(w) = 274,000) ethylene octadecene (“OD”)copolymer; 30 mole % OD^(d)Polypropylene Tg used in calculation eq(2) is 273° K.

Example 2

Density results for two blends of aPP (described in Example 1) withcopolymers 1 and 2 are compared with the density of the unblended aPPare reported in Table 4. Density was measured using a density gradientcolumn (ASTM D-792). TABLE 4 Density Comparison (23° C.): aPP versusExamples of Plasticized aPP Density, g/cm3 Copolymer Copolymer Liquid,wt % @23° C. None 0 0.8525 Copolymer 1 50 0.8591 Copolymer 2 50 0.8592

The density measured for the unblended aPP is comparable to thosereported for amorphous polypropylene in the literature. The increaseddensity (0.007 g/cm) of the blends relative to the unblended aPPindicates a substantial reduction in “void volume”. This reduction invoid volume is suggestive of miscibility of the blends.

Example 3

Dynamic mechanical thermal analysis of the 50:50 blend of aPP (Example1)+Copolymer 1 was measure, and the results illustrated in FIG. 2. Thepeak in tan δ occurs at 245° K and is illustrated in FIG. 3. This valueis in good agreement with the Tg measured for this blend by DSC at ascan rate of 10° C. per minute (242° K). DMTA of this same aPP withoutplasticizer gives a peak at 276° K.

DMTA's were measured (not illustrated) for two other blends: ePP(Example 1)+Copolymer 3 and aPP (Example 1)+Copolymer 3. The T_(g)'smeasured from DMTA and DSC for these three blends are compared in Table5. Agreement between the two methods is good. TABLE 5 Comparison of TgMeasured by DSC and DMTA Blend Thermoplastic Tg, ° K Polymer (wt %)Copolymer (wt %) DSC DMTA e-PP^(a) (60) Copolymer 2 (40) 256 258a-PP^(a) (50) Copolymer 2 (50) 245 247 a-PP^(a) (50) Copolymer 1 (50)242 245^(a)The thermoplastic polymers described in Example 1.

In all three blend DMTA's, the tan δ peak was substantially broader thanthat for the pure aPP, and markedly skewed to higher temperature aswell.

FIG. 4 illustrates NMR relaxation measurements (T_(1ρH)) for the blendof aPP and Copolymer 2

Procedure:

The NMR data were obtained on a Bruker DSX-500 spectrometer using avariable-temperature 4-mm MAS probe. Radio-frequency power levels were70 kHz for spin-locking and decoupling, corresponding to a H π/2 pulseof 3.5 microseconds. Data were collected at MAS speeds of 4.5-5 kHz.Depending on the temperature, anywhere from 100 to 2,000 scans werecollected per relaxation time increments. T_(1ρH) measurements were madeusing standard ¹³C cross-polarization observations experiments, in whichthe length of the H spin-lock pulse was incrementally varied prior tocross-polarization. The blend was prepared in toluene solutionscontaining a BHT stabilizer, and dried under nitrogen at ambienttemperature, with further drying at 50° C. in vacuum for 48 hours.

NMR relaxation measurements also demonstrate miscibility between aPP andCopolymer 2 (50:50 wt:wt).

Example 4

Storage modulus depression data were measured by DMTA as described inExample 1.

Storage modulus depression can be achieved through manipulation ofcrystallinity of the polypropylene as well as addition of plasticizer.The plateau storage modulus of reactor grade aPP (Example 1) at ambienttemperature is 0.47 Mpa, or just above 2×10−6 dynes/cm (the “DahlquistCriterion”) for adhesion. Addition of low molecular weight ethylenecopolymer plasticizer can depress the storage modulus at least anotherdecade or so, or well below the Dahlquist Criterion, thus rendering thepolymers exceptionally tacky. A new family of adhesives could be madebased on these blends where first the crystallinity of the polypropyleneis adjusted appropriately with a combination of tacticity defects andcomonomer then miscible liquid added to adjust and optimize the balanceof properties. Optionally, miscible tackifiers may also be used. Evenwith a melting point of 125° C.—corresponding to a crystallinity of just˜15% and total defects of ˜9-10 mole %—one would have a wide Tm-Tg usewindow on the order of 130-140° C.

Example 5

A summary of ambient temperature properties measured on tensile barsmade from a blend of isotactic polypropylene (PD-4062 resin) andCopolymer 2 is provided in Table 6. PD-4062 resin is a polypropylenehomopolymer available from Exxon Chemical. PD-4062 resin has a melt flowrate of 3.9 g/10 min (ASTM D 1238) and a density of 0.90 g/cm³ (ASTM D792).

Tensile Measurement Procedure

Approximately 3 grams of sample is placed in a 2.5″×2.5″×6 mil moldtemplate between two pieces of Teflon foil. This assembly is placedbetween the 6″×6″ platens of a Carver Press and heated to 190° C. for 2min. At this point the sample is compressed at 5,000 psi and 190° C. foran additional 2 min. The mold is then removed, placed on coolingplatens, and cooled to room temperature.

After the sample is removed from the mold, it is inspected for bubblesand imperfections. Tensile specimens are cut from areas having novisible imperfections using a standard micro “bog bone” cutter (5.5-6mil thickness, 0.08″ in width and 0.197 in length). Five samples werecut from each compression molded plaque. The samples were allowed to ageat least 48 hours before tensile measurements were carried out.

Each tensile specimen was tested on the Instron 4502 using serratedgrips set at 80 psi. The sample rate was 10 points per second at acrosshead speed of 2″/min. TABLE 6 Summary of Tensile Bar Data Recordedat Ambient Temperature for Blends of Copolymer 2 with isotacticpolypropylene (PD4062) Energy-to- Wt % Modulus Stress@Yield % Strain@MaxBreak Copolymer 2 (kpsi) (kpsi) Load (lbs-in) 6 50.3 4.77 845 2.75 12.540.5 4.1 822 3.18 18 33.2 3.52 690 2.24

Example 6

A summary of ambient temperature properties measured on tensile barsmade from a blend of isotactic polypropylene and Copolymer 3 is providedin Table 7. TABLE 7 Summary of Tensile Bar Data Recorded at AmbientTemperature for Blends of Copolymer 3 with isotactic polypropylene(PD4062) Wt % Modulus Stress @ Yield % Strain- Energy-to-Break Copolymer3 (kpsi) (kpsi) to-Brk (lbs-in) 0 55.0 5.68 503 2.29 10 41.6 4.32 8713.62 20 30.0 3.28 848 2.52

Example 7

FIG. 5 illustrates the roughly linearly decreasing effect on Young'smodulus of isotatic polypropylene by blending Copolymers 2 and 3 withisotactic polypropylene (PD4062). In keeping with the data shown in FIG.4 (DMTA data), the Young's modulus obtained from the tensile barsdecreases—roughly linearly—with increasing plasticizer content. Inaddition, the energy-to-break for the tensile bars increases over 50%due to addition of ˜5-15 wt % plasticizer (maximum around 10 wt %) asillustrated in FIG. 6).

Example 8

An examination of the large strain behavior/recovery of a very soft [ePP(described in Example 1)+Copolymer 2] 60:40 wt:wt blend was undertaken.A hysterisis series of tensile curves (A J Peacock procedure) is shownin FIG. 7. Elastic recovery of this material is ˜90% 24 hours after1000% elongation. Elongation to break is ˜1400%.

Hysterisis Test Procedure

The hysterisis tests were conducted on the Instron 1123D. The filmhysteresis testing procedure used is an Exxon variation of a proceduredescribed by DuPont in its brochure on its polyether urethane elasticproduct, T-722a. In the Exxon variation, 1×6 inch strips are subjectedto successive % strains of 100, 200, 300, 400, 500 and 1,000% (jaw gapseparation of 2″ and crosshead speed of 20″/min). The sample is held for30 seconds at extension and then retracted and held at 60 seconds arelaxation prior to the next extension cycle. FIG. 8 illustrates thehysteresis stress/strain curve. Tables 8, 9 and 10 provide mechanicalproperties data for several polypropylene liquid blends and comparativedata for non-blended polypropylene. The mechanical data were generatedusing various tests that are listed in the first column of each Table.The procedures for conducting each such test are known and understood byone skilled in the art. TABLE 8 Escorene RCP PD4062 PD4062 3445 EscorenePD9272 10% 20% Escorene 10% 3445 RCP 10% EB P- PD4062 EB8D EB8D 3445EB8D 20% EB8D PD9272 42-27 Gardner Impact 220. 249.8 222.7 109.3 188.020.0 311.3 230.9 RT (B) (DB) (D) (D) (S) (DB) (D) (S) (DB) (D) (D)(in-lbs) (DB) Gardner Impact <8 <8 <8 <8 <8 <8 <8 <8 −29° C.(in-lbs)Notched Impact 0.578 0.895 1.159 0.356 0.518 0.388 1.312 1.551 RT(ft-lb/in) Notched Impact 0.269 0.178 0.257 0.206 0.219 0.136 0.1830.279 −18° C. (ft-lb/in) Notched Impact 0.181 0.215 0.189 0.206 0.1560.144 0.153 0.199 −40° C. (ft-lb/in)

TABLE 9 PD4062 PD4062 Escorene Escorene RCP 10% 20% Escorene 3445 344510% EB PD4062 EB8D EB8D 3445 10% EB8D 20% EB8D RCP P-42-27 1% SecantFlex 220873 133105 90491 172196 116355 72976 106957 71152 Mod (psi) 1%tangent 227616 140036 96440 175337 124411 78142 110312 74769 Flex Mod(psi) Flex Strength 2683 1575 1084 2070 1417 873 1290 859 (psi) Energyat peak 0.229 0.131 0.092 0.173 0.120 0.075 0.108 0.068 (in-lb)

TABLE 10 Escorene 3445 Escorene RCP PD4062 PD4062 Escorene 10% 3445 10%EB PD4062 10% EB8D 20% EB8D 3445 EB8D 20% EB8D RCP P-42-27 Yield Stress4922 3885 3045 4591 3569 2592 3316 2510 (psi) Elongation 19.5 29.0138.23 20.05 28.65 28.63 20.26 29.06 at Yield (%) Elongation 349.79998.02 998.84 357.08 558.36 55.53 998.40 998.21 at Break (%) Stress at3164 3187 2998 1617 1490 2355 3067 2586 Break (psi) Youngs 85591 4766926191 74097 43446 27465 44123 27310 Modulus (psi) Energy @ 1369 35063147 1162 1663 151 2878 2468 Break (in-lb)“B” means brittle,“S” means strings“DB” means ductile brittle and“D” means ductile.PD4062 is a polypropylene homopolymer described in Example 5Escorene 3445 is a polypropylene homopolymer available from ExxonChemical. MFR 35 g/10 min (ASTM D1238) Density 0.90 g/cm³ (ASTM D792)RCP PD9272 is a polypropylene/ethylene random copolymer available fromExxon Chemical. MFR 2.9 g/10 min (ASTM D1238) Density 0.89 g/cm³ (ASTMD792)EB8D is a an ethylene(24 wt %) propylene (76 wt %) copolymer, 4000 Mn.P 42-27 is an ethylene (51 wt %) butene (49 wt %) copolymer, 5184 Mn.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to many differentvariations not illustrated herein. For these reasons, then, referenceshould be made solely to the appended claims for purpose of determiningthe true scope of the present invention.

Although the appendant claims have single appendencies in accordancewith U.S. patent practice, each of the features in any of the appendantclaims can be combined with each of the features of other appendantclaims of the independent claim.

1-10. (canceled)
 11. A plasticized polypropylene thermoplasticcomposition comprising: a blend of a thermoplastic polymer and anethylene copolymer, wherein the thermoplastic polymer comprisesisotactic polypropylene, syndiotactic polypropylene and or atacticpolypropylene, said thermoplastic polymer having a melt flow rate (MFR)(ASTM D1238) of from 0.3 to 1000; wherein the ethylene copolymer has aweight-average molecular weight (M_(w)) (GPC) of from 500 to 10,000, amolecular weight distribution (MWD) (GPC) of from greater than 1.5 toless than or equal to 3.5, and comprises 20 mol % to 70 mol % of acomonomer selected from the group consisting of C₃ to C₂₀ linear orbranched alpha-olefins or diolefins.
 12. The plasticized polypropylenethermoplastic composition of claim 11, where the thermoplastic polymerA) has a crystallinity by DSC at a scan rate of 10° C. per minute ofless than 60% and the wt % of said ethylene copolymer wherein the wt %of said ethylene copolymer in the thermoplastic composition is less thanor equal to y, wherein y is in the range of 0.1 to 50, as determined byy in the equationy=50−0.5x where x=the % crystallinity of said thermoplastic polymer. 13.The plasticized polypropylene thermoplastic composition of claim 11wherein the thermoplastic polymer has a crystallinity by differentialscanning calorimetry of greater than 60% and the ethylene copolymer ispresent at up to 20 weight %.
 14. The plasticized polypropylenethermoplastic composition of claim 11, where the thermoplastic polymerA) has a crystallinity by DSC at a scan rate of 10° C. per minute ofless than 5%.
 15. The plasticized polypropylene thermoplasticcomposition of claim 11 wherein the thermoplastic polymer has an Mn offrom 60,000 to 750,000.
 16. The plasticized polypropylene thermoplasticcomposition of claim 11 wherein the thermoplastic polymer has a meltingpoint less than 162 ° C.
 17. The plasticized polypropylene thermoplasticcomposition of claim 11 wherein the thermoplastic polymer has a hexaneextractables level of less than 2 weight %.
 18. The plasticizedpolypropylene thermoplastic composition of claim 11 wherein thethermoplastic polymer further comprises ethylene-propylene rubber,ethylene propylene diene rubber and or an ethylene plastomer.
 19. Thepolypropylene thermoplastic composition of claim 11 further comprising athermoplastic polypropylene modifier compound present at greater than0.001 wt % of the total blend and is selected from one or more of thegroup consisting of antioxidants, fillers, pigments, hydrocarbon resins,rosins or rosin esters, waxes, UV stabilizers, and additionalplasticizers.
 20. A plasticized polypropylene composition, comprising ablend of: a) 50-99.9 wt % of an isotactic thermoplastic polymercomprising propylene derived units, optionally further comprising one ormore copolymerizable monomers selected from C₂-C₁₀ olefin, diolefin, orcombinations thereof, said polymer comprising a crystallinity, bydifferential scanning calorimetry of from 10-70%; b) 0.1-50 wt % of atleast one ethylene copolymer having a weight average molecular weight of500-10,000, a molecular weight distribution (MWD) by gel permeationchromatography (GPC) of ≧1.5 or ≦3.5, and a comonomer content of: 1) ≧20mole % to ≦54 mole % when the comonomer is propylene; 2) ≧20 mole % to≦48 mole % when the comonomer is 1-butene; 3) ≧20 mole % to ≦37 mole %when the comonomer is 1-hexene; 4) ≧20 mole % to ≦31 mole % when thecomonomer is 1-octene; or 5) ≧20 mole % to ≦27(?) mole % when thecomonorner is 1-decene.